Illuminated signage, advertising and display boards are in popular use across the world. These signs usually incorporate discrete lighting which has the effect of illuminating the whole of the sign. There have been a number of past suggestions for using translucent plastics with edge lighting whereby the light is released by a matrix of dots to fully and evenly illuminate the entire surface area of the sign. Well known arrangements of this type of sign utilise an acrylic panel that has printed thereon a graded matrix of ink dots on one or both faces of the panel.
The dots of ink affect the refractive and reflective nature of the acrylic and allow light introduced along an edge of the panel to be released across the whole surface area of the panel. When the dots are carried on both sides, the light reflects and refracts more effectively through both surfaces. In one option, a reflective film or sheet is placed on one side causing the light released on that side to be reflected back through the panel so the majority of light leaves the panel only through one (“front”) surface.
The same process of controlled, even light release can be achieved by laser etching the surface of an acrylic panel.
A problem with lighting systems of the kind described above is that the acrylic panel which carries the matrix of printed dots or laser etching has to be handled very carefully. If the panel becomes scratched or subjected to moisture, light escapes as bright spots thereby upsetting the even light distribution across the surface of the panel. The vulnerability of the surfaces of the acrylic panel reduces the effective use of such panels.
Furthermore, these panels cannot by themselves, operate as structural elements. In order to be used as structural elements they must incorporate a supporting skeleton such as an edge frame.
Other, small non-structural illumination panels are also used as illuminating screens for liquid crystal displays in devices such as calculators and mobile phones. The planar elements of these panels are typically held together by the calculator or phone casing, or some other mechanical means such as screws.
It is consideration of the problems associated with these structures that has brought about the present invention.